Transition Metal-Catalyzed Asymmetric Reactions Using P-Chirogenic Diaminophosphine Oxides: DIAPHOXs
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This review describes the development of a new class of chiral phosphorus ligands: amino acid-derived P-chirogenic diaminophosphine oxides, DIAPHOXs, and their application to several transition metal-catalyzed asymmetric allylic substitution reactions. Pd-catalyzed asymmetric allylic alkylation with cyclic β-keto esters as prochiral nucleophiles was initially examined using P-chirogenic diaminophosphine oxide la, resulting in highly enantioselective construction of quaternary stereocenters. Mechanistic investigations revealed that la is activated by N, O-bis (trimethylsilyl) acetamide-induced tautomerization to afford a trivalent diamidophosphite species 13, which functions as the actual ligand. Pd-catalyzed asymmetric allylic substitutions of both acyclic and cyclic sub-strates were also examined using various nucleophiles such as malonate derivatives, nitromethane, aliphatic amines, and aromatic amines, providing a variety of chiral compounds with good to excellent enantioselectivity. In addition, Ir-catalyzed asymmetric allylic amination and alkylation of terminal allylic carbonates were examined using structurally optimized P-chirogenic diaminophosphine oxides, and the corresponding branched products were obtained in a highly regio-and enantioselective manner. Furthermore, the developed catalytic asymmetric process was successfully applied to the catalytic enantioselective synthesis of biologically active com-pounds, (R)-preclamol, (R)-baclofen hydrochloride, and (-)-paroxetine.
- 2008-09-01
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関連論文
- Transition Metal-Catalyzed Asymmetric Reactions Using P-Chirogenic Diaminophosphine Oxides: DIAPHOXs
- Synthesis of Novel Bidentate P-Chiral Diaminophosphine Oxide Preligands: Application to Pd-Catalyzed Asymmetric Allylic Substitution Reactions